Fluconazole

Fluconazole is a triazole medicine used to treat fungal infections. It is effective against a broad spectrum of fungi including:

Dermatophytes (tinea infections)

Yeasts such as candida and malassezia.

Systemic infections such as cryptococcosis and coccidiodomycosis

In New Zealand, fluconazole is available as 50 mg, 150 mg and 200 mg capsules on prescription (Diflucan®). There is also a 2 mg/ml injection for intravenous use. In New Zealand, Pharmaceutical Schedule subsidy of the capsules requires Specialist recommendation.

Fluconazole binds to the fungal p450 enzymes and stops the cells making ergosterol, the main component of the cell wall.

Fluconazole is well absorbed orally with or without food. It is widely distributed in body tissues. It takes 22 to 30 hours for half of the medication to be cleared from the blood stream and may take several days of continuous treatment to reach a steady concentration. The drug is eliminated unchanged in the urine so doses should be reduced if there is kidney disease.

Dose regime for oral fluconazole

For vulvovaginal candidiasis, a single oral dose of fluconazole 150 mg is usually effective. It can be repeated.

For dermatophyte (tinea) infections and pityriasis versicolor, either 50 mg daily or 150 mg once weekly is taken for two to six weeks.

Once-weekly fluconazole is often used off-label to treat toenail fungal infections (onychomycosis).

Fluconazole should not normally be taken in pregnancy. Use during breast-feeding is not generally recommended, because the drug is found in breast milk.

Drug interactions with fluconazole

Unfortunately, fluconazole can interact with other medications.

Fluconazole should not be taken with the HMG Co-A reductase inhibitor simvastatin, and the dose of atorvastatin should be reduced. Pravastatin and rosuvastatin are preferable. Toxicity results in muscle pain and weakness, which may be serious.

Fluconazole may increase the concentration of these drugs and enhance their effect: